Experiments with magnets and our surroundings


What is attracted to magnets?

Take a wand magnet and go around the house to see what will stick to it or feel like it is attracted to it. Keep a list of the items you tried, and if the attraction was strong, weak, or none.  Then try to figure out why.

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Try especially different types of metals, for example:

    iron and steel    (nails, screws and nuts)
    stainless steel    (special hardware, some kitchen sinks, most everyday forks and spoons)
    brass    (special screws, kick-plates on front doors)
    zinc    (battery case)
    copper    (old pennies, copper pipes)
    bronze    (marine bell)
    aluminum    (foil)
    silver    (expensive silverware, some jewelry)
    gold    (wedding rings, grandma's teeth)
    mercury    (thermometer - no need to break the thermometer to do the test)
    nickel    (some coins, US nickels are made of 75% copper!, try Canadian nickels)
    tungsten    (filament in light bulb)
    magnesium    (from a science supply store, used in a ribbon form for burning in air, or from a hardware store that carries magnesium floats for working with concrete)
    coins from several countries    (try Canada, England, China, Japan, Germany)

About the US coins, I know the following:
Before 1982, the penny was 95% copper.  After that, it was changed to 2.6% copper.   It is mostly a zinc alloy with a copper coating.
The nickel is 75% copper.
The dime, quarter and half dollar is 91.67% copper.
The Susan B. Anthony dollar is 87.5% copper.
The new gold-colored dollar is 90% copper.

To learn more about some of these metals, check out the pendulum experiment.

Below is a photo showing some of these metals, and a photo showing copper balls.   (I got the copper balls from at gift shop in the UP of Michigan, at Big Springs State Park, just north of Manistique.)  The cylinder of titanium was from a jet engine exhaust system.

 cuballs.jpg (4179 bytes)

Minerals expt.gif (888 bytes)

Besides seeing what effect a strong magnet has on different metals, try and find out the effect it has on different minerals.   A great source of minerals is found in the shops of most public, natural and science museums and in science shops or nature stores at malls. They usually have a stand with several different types of colorful minerals displayed; often the pieces are highly polished.  They come with a small card describing the mineral, and cost about $1 per item. 

min01.jpg (1767 bytes) min02.jpg (1483 bytes) min03.jpg (1673 bytes) min04.jpg (1450 bytes)
Rose quartz                       Blue lace agate                   Jasper                               Chalcedony

min05.jpg (1378 bytes) min06.jpg (2450 bytes) min07.jpg (2015 bytes) min08.jpg (1820 bytes)
Sodalite                             Tourmaline                         Snowflake obsidian           Obsidian

min09.jpg (2216 bytes) min10.jpg (3364 bytes) min11.jpg (2651 bytes) min12.jpg (2789 bytes)
Bornite (Peacock ore)       Silicon                               Pyrite                                Galena

min13.jpg (3979 bytes) min14.jpg (2097 bytes) min15.jpg (2357 bytes) min16.jpg (2677 bytes)
Quartz                               Tektite                              Lodestone                         Hematite

min17.jpg (2866 bytes) min19.jpg (2581 bytes) min20.jpg (2280 bytes) min21.jpg (2538 bytes)
Bismuth                             Lodestone                         Tigereye                            Blue calcite

min22.jpg (1447 bytes) min23.jpg (3313 bytes)
Magnetite                          Iceland Spar (interesting optical properties)

 

In particular, try minerals with iron or nickel in them. An interesting science fair project would be to have several types of minerals on display along with a wand magnet. You can see which minerals are strongly attracted to the magnet (can be picked up by the magnet), which are slightly attracted to the magnet, and which are not attracted at all.   Try to predict what category each would fall into.

Here are some minerals I know are strongly or slightly attracted to magnets:

    Hematite  
(This is usually the very shiny, black, heavy mineral found in the displays, shown at the left in the first  photo.  Some jewelry is made of hematite.)
    Magnetite  
(This may very likely be a weak magnet by itself! Remember, this was what started the whole study of magnetism to begin with in ancient Greece. This is seen in the fifth photo above.)
    Lodestone (similar to magnetite, but without the cubic crystalline form)
    Franklinite
    Chromite
    Ilmenite
    Pyrrhotite

Don't forget to try pyrite (also known as "fool’s gold", made of iron and sulfur), cobaltite, zincite, arsenopyrite, skutterudites, obsidian
(also known as Apache Tears) and others. 

To make the project more colorful and interesting, I also have some silicon, tektite, tourmaline, quartz, marble, tiger-eye, peacock ore, bismuth and others minerals.   Possible selection of minerals from Edmund 81-632.  Also check this site for more as a source for minerals and other interesting links:
  http://www.greatsouth.net/

I found some magnetized stones that looked like hematite but they would stick to each other!  I was at Wonderworks in Orlando, Florida when I spotted them.  Now, hematite cannot be permanently magnetized.  So, how do they do that?  They are actually ferrite magnets that have been polished to look like hematite and then magnetized.  I had heard about spheres of these that would stick together making a bracelet, too.   

Ferrofluids expt.gif (888 bytes)

The area of ferrofluids is quite new, and very interesting.  Ferrofluid is made of small particles (~10nm) of magnetite (Fe3O4) surrounded by a surfactant such as tetramethylammonium hydroxide.  The surfactant is needed to keep the particles of magnetite from agglomerating (clumping together) due to magnetic and van der Waals interactions.  It's like having a slippery skin around the small particle of magnetite.  Thermal motion helps, but is not sufficient by itself.  A group of these prepared particles is like a solution that acts like a medium density liquid which is affected by magnetic fields.  When a magnet is brought near it, the liquid splits up and starts to group itself into spikes or hairs along the magnetic field lines as shown in the photos.  It is used to seal rotating shafts, and in speakers to help dampen the vibrations of the speaker coil, and help cool the coil.  Great stuff to play with!

Here are some photos of what you can do with a vial of ferrofluid (I purchased the kit FF-100 from Educational Innovations as well as the separate preform display cell FF-200 sitting in front.)  When storing the preform display cell, it is best to sit it onto its cap.  This keeps the interior walls cleanest.    Cost for the kit is about $50.  Cost for the preform cell is about $17.
Arbor, Edmund 82-215, AS&S, EdIn FF-100, FF-200.
Another source for Ferrofluid is from CZFerro.  Their kits are quite reasonable, and come with a pair of magnets with which you can manipulate the fluid.

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Other Objects expt.gif (888 bytes)

Try other materials, too, like wood, plastic, carbon, cotton, wool, glass, concrete, leaves, CDs, and so on, which you can find around the house.

 magvcr02.jpg (3631 bytes) bill1.jpg (2964 bytes) bill2.jpg (3202 bytes)

Some things which will be attracted to or stick to a very strong magnet, like a rare-earth magnet, is the tape from a VCR or audio tape, a dollar bill, and the surface of a floppy disk.  The reason these items will stick to a magnet is because of the very small particles of iron used in the ink of the dollar bill, and the iron oxide (ferric oxide) used as the recording medium for the VCR and audio tapes and for the floppy disk.  (Please only use a tape or disk which you want to destroy!) 

Let's try an experiment:
As you can see in the photo above, the tape from a VCR is attracted to the rare-earth magnet.  The magnet will erase the information contained on that section of the VCR tape.  I used a pencil to hold open the flip-top cover. 

How about a dollar bill?
On the other two photos, you can see how the bill is attracted to the rare-earth magnet. 
Take a crisp bill.
Fold it about 55% of the way along its length.
Lay it on a table as shown with the longer portion on the table, the shorter portion sticking up.
Bring the magnet close to the edge of the bill.
Watch the bill spring toward the magnet.
The reason for the attraction is that the ink on the bill has some iron particles in it.

To see what effect a magnet has on floppy disks:
Take a floppy disk and try these things with it.   Be sure to record exactly what you do and your observations - the two most important parts of an experiment!
Be sure to try some typical refrigerator magnets (usually very weak since they can barely hold one piece of paper to the fridge door) as well as some stronger rare-earth magnets (neodymium-iron-boron magnets which can easily hold a stack of 20 sheets to the fridge).
Also, vary how the magnet approaches the floppy disk and leaves the disk.
  For example - directly toward it, perpendicular to the plane of the disk,
  or across the face of the disk, in parallel to the plane of the disk.
  Perhaps a quick approach and a slow approach could also be compared.
Try the top side and the bottom side of the disk.
Even try moving the magnet around in a circle on the face of the disk.
Maybe even have a floppy held to the fridge by a magnet for a week to see if time has any affect.
If you can make an AC electromagnet, that would also be a great addition for comparison.

What kind of data will you put on the disk in order to see if the data has been corrupted?
Perhaps some bitmap images would work well, with a simple pattern of black and white squares. They are usually large files so they would cover a large part of the disk. Also, looking at the image would be a very quick and easy way to determine if any bits were changed.
Another method would be to have a large data file on the disk, and do a file compare to the original which is kept on the hard drive.

Want to try something a bit unusual?  You know that several cereals claim to be "iron fortified".  How do they do that?  By adding some finely powdered iron (like small iron filings) in with the cereal as it is being mixed.  To see this, simply do the following:
    a.  Get some cereal that has a large percentage of the RDA (Recommended Dietary Allowance) for iron, and pour half a serving into a bowl.
    b.  Add water (no need to waste the milk) to the cereal.
    c.  Mix up the stuff so that it is a watery slurry, not very thick.
    d.  Take a strong rare-earth magnet and place it into an inside-out zip-lock bag.  The purpose for the bag is to keep the surface of the magnet free from iron particles which are very difficult to get off.
    e.  Move the bagged magnet around in the slurry of the cereal.
    f.  After a minute, take the magnet and its plastic bag out of the slurry, and examine it to see small, dark specks attached to the plastic at the magnet.  This is metallic iron.
    g.  Unfortunately, our bodies can not absorb metallic iron very well, so this really does not help with our intake of iron.   It would be better to take a supplementary multi-vitamin/mineral pill which contains an absorbable iron.   The iron is needed to help form hemoglobin, which is the pigment in red blood cells responsible for transporting oxygen.
    h.  You can now turn the bag outside in and carefully remove the magnet from the zip-lock bag.  This will keep the iron filings inside the bag and off the magnet.
    http://www.stevespanglerscience.com/experiment/00000034

Conclusions

What did you find out?  Do you now have a fairly extensive list of things magnets can and cannot attract?
Check out this information as well:

    http://www.eskimo.com/~billb/miscon/miscon4.html#iron

For more information on various minerals, a great source is:

    The Audubon Society Field Guide to North American Rocks and Minerals
        ISBN 0-394-50269-8

    Another site for obtaining various minerals is: 

Problem with 2 or 3 unknown rods

Suppose you are given 2 metal rods:  one is a magnet, the other is made of iron.  However, both of them are painted so they appear to be the same.  Their weight is the same.  You are in a room with no windows so you can't tell where North is located.  You have no other objects with you.  How will you be able to determine which rod is the magnet and which rod is iron?

Suppose you are given 3 metal rods:  one is a magnet, one is made of iron, and one is made of brass.  However, all of them are painted so they appear to be the same.  Their weight is the same.  You are in a room with no windows so you can't tell where North is located.  You have no other objects with you.  How will you be able to determine which rod is the magnet, which rod is iron, and which rod is brass? 

Check here for the answer.

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